I recently switched on phpBB3 version, and ran into a few problems.
The first one:

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The words can be barely seen on this background, and I'm not willing to change the color of the font. How do I change the background?

The second one:

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As you can see, the "Code" word is not visible until it's highlighted, and the background of the code is too bright. How do I change both colors?

My apologizes if this is re-posting. I tried every code I found, but none worked.
Thanks in advance!

Code:

dl.codebox dt {
color: black;}

Thank you, but what about the Code background?

Code:

background-image: url('IMAGE URL');}

It's still white

Code:

dl.codebox dt {
color: black;
background-image: url('IMAGE URL');}

Yeah, I know, the thing is, only background of the "Code:" changes, and I want the whole code box to change the color.

Code:

background-color: black;}

This is what I got:

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And I want the whole codebox to be black.

On my forum test code works and change the whole color of "Code" , perhaps you have antother css code for "code box". Check please.

I checked and there is no other code for it.